function s1_read_last_two_bytes_of_a_mbr_backup_file(){
   local file_path=$1
   local last_bytes=$(tail -c 2 "$file_path" | od -A n -t x1 | tr -d ' \n')
   if [ "$last_bytes" = "55aa" ];then
       echo "YES"
   else
       echo "NO"
   fi
}

function s2_read_mbr_partition_table_info(){
   #path="$1"
   #partition_table_start=$(hexdump -s 446 0n 16 -e '/1 "%02x "' "$path" | sed 's/ $//')
   #for i in {0..3}; do
   #offset=$((partition_table_start + i * 16))
   #start_sector=$(hexdump -s $offset -n 4 -e '/1 "%d\n"' "$path")
   #end_sector=$(hexdump -s $((offset +4)) -n 4 -e '/1 "%d\n"' "$path")
   #echo "$start_sector $end
for i in {0..3}; do
offset=$((446 + i * 16))
start_sector=$(dd if="$1" bs=1 skip=$((offset + 8)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n')
if ! [[ $start_sector =~ ^[0-9]+$ ]];then
continue
fi
if [ "$start_sector" -eq 0 ];then
continue
fi
size_sector=$(dd if="$1" bs=1 skip=$((offset + 12)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n')
end_sector=$((start_sector + size_sector - 1))
echo "$start_sector $end_sector"
done
}

function s3_parse_partition_info(){
   fdisk_output=$(cat)
   disk_size_bytes=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $5}')
   disk_size_sectors=$(echo "$fdisk_output" | grep "Disk /dev/vad:" | awk '{print $7}')
   physical_sector_size=$(echo "$fdisk_output" | grep "Sector size" | awk '{print $4}')
   first_partition_start_sector=$(echo "$fdisk_output" | grep "/dev/vad1" | awk '{print $3}')
   first_partition_end_sector=$(echo "$fdisk_output" | grep "/dev/vad1" | awk '{print $4}')
   first_partition_typr=$(echo "$fdisk_output" | grep "/dev/vad1" | awk '{print $8}')
   echo "disk size in bytes:$disk_size_bytes"
   echo "disk size in sectors:$disk_size_sectors"
   echo "physical sector size in bytes:$physical_sector_size"
   echo "first partition start sector id:$first_partition_start_sector"
   echo "first partition end sector id:$first_partition_end_sector"
   echo "first partition type:$first_partition_type"
}

function s4_run_passwd_as_plain_user_and_get_status(){
   oversleeping_path=$(which oversleeping)
   chown root "$oversleeping_path"
   chmod 755 "$oversleeping_path"
   $oversleeping_path &
   ps -o uid,euid,ruid -C 'oversleeping' | awk 'NR>1 {print $1","$2","$3}'
}

function s5_add_a_scheduled_task(){
   echo "*/5 * * * * date +\%Y\%m\%d_\%H\%M\%S >> $HOME/test_crontab" | crontab
}

